The present invention relates to a semiconductor device test method.
An IC socket that matches the shape of the device to be measured is employed to test a newly developed device in the prior art. An IC socket, which comes into electrical contact with the device to be measured, fulfills a function as a means for electrical signal communication between a peripheral device and the device to be measured.
Now, the IC socket, the device to be measured and the connection between the IC socket and the device to be measured are explained in reference to FIGS. 29, 30 and 31.
FIG. 29 is a sectional view of a device to be measured 1 and an IC socket 3 mounted at a circuit board 5, illustrating the connections among them. The IC socket 3 is provided with a plurality of contacts 3a, and is soldered onto the circuit board 5 at the contacts 3a. The device to be measured 1, which is pressed down by a holding member 7, is electrically connected with the contacts 3a of the IC socket 3.
FIG. 30 is a perspective of the device to be measured 1, showing its surface on which electrodes are formed. The device to be measured 1 is a CSP (chip-size package) device achieved through chip size packaging. The device to be measured 1 is provided with a plurality of electrodes 1a through which electrical signals are input and output and power is supplied. The individual contacts 3a provided at the IC socket 3 are positioned so that they come in contact with the corresponding electrodes 1a. 
FIG. 31 is a plan view of the circuit board 5 with the devices to be measured 1 and the IC sockets 3 mounted, viewed from above. The circuit board 5 is allowed to engage in electrical signal communication with peripheral devices such as an IC tester and a burn-in apparatus (not shown) via connection terminals 5a and 5b. 
With the devices to be measured 1, the IC socket 3 and the circuit board 5 configured as described above, electrical signals input to the circuit board 5 from peripheral devices via the connection terminals 5a and 5b and a source voltage travel through the contacts 3a of the IC socket 3 to be supplied to the devices to be measured 1 through the electrodes 1a. In addition, electrical signals output by the devices to be measured 1 travel through the reverse route to reach the peripheral devices. Such an electrical connection enables functional tests on the devices 1 to be measured.
Apart from functional tests achieved by employing IC sockets as described above, a functional test on a wafer-level device, in particular, is implemented by adopting a method whereby probes are placed in contact with wafer pads constituting signal input/output electrodes and source electrodes of the device.
Since the wafer and the probes are placed in contact a great number of times in such functional tests employing probes, the contact durability of the probe is a critical concern. If the contact durability of the probes is poor, the cost of the functional test is bound to increase, raising the price of the device itself. For this reason, probes are normally constituted of materials with a high degree of hardness such as tungsten and beryllium copper.
FIG. 32 illustrates a probe card 13 provided with probes 11. At the probe card 13, a specific circuit that corresponds to the device to be measured is printed, and electrical signal communication with peripheral devices (not shown) is enabled via connection terminals 13a and 13b. 
The positional relationship between a probe card 13 and the wafer 15 which constitutes the device to be measured is illustrated in FIG. 33. Electrical signals provided by a peripheral device are input to the probe card 13 via the connection terminals 13a and 13b, travel through the circuit formed at the probe card 13 to reach the probe 11. Then, the electrical signals are applied to the pads formed at the wafer 15 from the probe 11. In addition, electrical signals output by the wafer 15 travel through the reverse route to reach a peripheral device. The structure described above enables a functional test on the wafer 15.
However, the following problems are yet to be addressed in functional tests conducted by utilizing IC sockets and functional tests conducted by utilizing probes.
The smallest pitch for contacts at an IC socket is currently 0.65 mm. At the same time, the package size has been reduced in recent years, with the CSP being a typical example, and as a result, the electrode pitch at the device has been switched from 1.27 mm to 0.8 mm or 0.5 mm. This reduction in the electrode pitch at the device necessitates a reduction in the pitch of the contacts at the IC socket.
However, in order to reduce the contact pitch at an IC socket to 0.65 mm or smaller, the IC socket machining accuracy must be improved. This will inevitably raise the production cost of the IC socket, and may result in a large increase in the device price.
In addition, the body size of IC sockets imposes a restriction upon the number of IC sockets that can be mounted at a circuit board. Such restriction on the number of IC sockets that can be mounted at the circuit board ultimately restricts the number of devices that can be tested in a single functional test. Thus, functional tests conducted on devices utilizing IC sockets in the prior art are not always efficient.
In order to achieve a higher degree of efficiency in functional tests conducted by employing probes, it is desirable to increase the number of probes mounted at a probe card so that many devices can be tested at once. However, probes are secured to the probe card using a resin or the like in the prior art, which requires a large space for securing them. Thus, it is difficult to increase the number of probes without increasing the probe card size.
Furthermore, as higher integration of devices becomes more common, the pitch of the device pads with which probes come in contact is becoming narrower. This reduction in the pad pitch necessitates a reduction in the pitch of probes mounted at the probe card. However, it is difficult to reduce the probe pitch in the structure adopted in the prior art.